The Complete Codes

  NP-Completeness Most of the problems considered up to now can be solved by algorithms in worst-case polynomial time. There are many problems and it is not necessary that all the problems have an apparent solution. This concept, somehow, can be applied to solving the problem using computers. The computer can solve: some problems in a limited time e.g. sorting, some problems require an unmanageable amount of time e.g. Hamiltonian cycles, and some problems cannot be solved e.g. I-lasting Problem. In this section, we concentrate on the specific class of problems called NP-complete problems (will be defined later). Tractable and Intractable Problems We call problems as tractable or easy if the problem can be solved using polynomial-time algorithms. The problems that cannot be solved in polynomial time but require a super polynomial-time algorithm are called intractable or hard problems. There are many problems for which no algorithm with running time better than exponential time is kn

  Introduction:- ±    C is a general-purpose high-level language ±    Father of C – Dennis Ritchie ±    Originally developed for the UNIX operating system ±    Implemented on the Digital Equipment Corporation, PDP-11 computer in 1972 ±    The UNIX operating system and all UNIX applications are written in the C language   C has now become a widely used professional language for various reasons: ±     Easy to learn ±     Structured language ±     It produces efficient programs ±     It can handle low-level activities ±     It can be compiled on a variety of computers Why we use C? ±    C was initially used for system development work, in particular the programs that make-up the operating system ±    C was adopted as a system development language because it produces code that runs nearly as fast as code written in assembly language. ±    Some examples of the use of C might be: °     Operating Systems °     Language Compilers  °     Assemblers °     Text Editors °     Network Drivers °   

Scope of Variables All variables in a program may not be accessible at all locations in that program. This depends on where you have declared a variable. The scope of a variable determines the portion of the program where you can access a particular identifier. There are two basic scopes of variables in Python − Global variables Local variables Global vs. Local variables Variables that are defined inside a function body has a local scope, and those defined outside have a global scope. This means that local variables can be accessed only inside the function in which they are declared, whereas global variables can be accessed throughout the program body by all functions. When you call a function, the variables declared inside it are brought into scope. Following is a simple example − total = 0; # This is global variable. # Function definition is here      def sum( arg1, arg2 ): # Add both the parameters and return them."      total = arg1 + arg2; # Here total

Digital signatures A digital signature or digital signature scheme is a mathematical scheme for demonstrating the authenticity of a digital message or document. A valid digital signature gives a recipient reason to believe that the message was created by a known sender such that they cannot deny sending it (authentication and non-repudiation) and that the message was not altered in transit (integrity). Digital signatures are commonly used for software distribution, financial transactions, and in other cases where it is important to detect forgery or tampering. A digital signature (NOT a digital certificate) is an electronic signature that can be used to authenticate the identity of the sender of a message or the signer of a document, and possibly to ensure that the original content of the message or document that has been sent is unchanged. Digital signatures are easily transportable, cannot be imitated by someone else, and can be automatically time-stamped. The ability to ensur

NETWORK SECURITY Network security consists of the provisions and policies adopted by a network administrator to prevent and monitor unauthorized access, misuse, modification, or denial of a computer network and network-accessible resources. Network security involves the authorization of access to data in a network, which is controlled by the network administrator. Users choose or are assigned an ID and password or other authenticating information that allows them access to information and programs within their authority. Network security concerns: Secrecy Secrecy has to do with keeping information out of the hands of unauthorized users. This is what usually comes to mind when people think about network security. Authentication Authentication deals with determining whom you are talking to before revealing sensitive information or entering into a business deal. Non-repudiation and Integrity Control Non-repudiation deals related with signatures. Assurance that a m

HISTORY OF HTML In 1980, physicist Tim-Berners-Lee, a contractor at CERN proposed internet-based hypertext system. It was formally defined by Internet Engineering Task Force (IETF). After the development of Html, IETF created an Html working group. The HTML working group developed Html 2.0 in 1995. The combined work of the World Wide Web Consortium (W3C) and Web Hypertext Application Technology Working Group (WHATWG) released a greater number of advanced Html versions Html 3.2 in 1997, Html 4.0 in 1997, Html 4.01 in 1999 After a long interval, Html released a new version called Html5 in 2014. Html5 enhances the web pages to a new world. In 2016 Html 5.1 version was released by W3C. Now let's have a brief history of versions of HTML that we have till now. HTML 1.0 HTML 1.0 was the first release of HTML to the world. Not many people were involved in website creation at the time, and the language was very limiting. There really wasn’t much you could do with it b

Computer-Aided Software Engineering (CASE) Tools Computer-aided systems engineering (CASE) tools are the software programs that help the development team do their jobs more efficiently and more effectively. These tools support the drawing and analysis of system models. Some CASE tools also provide prototyping and code generation capabilities. Some examples are: Oracle’s Designer 2000, Rational’s Rose, Platinum’s Erwin, Popkin’s System Architect 001, and Visible System’s Visible Analyst. At the center of any CASE tool’s architecture is a developer’s database called a CASE repository. CASE repository is a system developer’s database where developers can store system models, detailed description and specification, and other products of system development. It is also called dictionary or encyclopedia. Around the CASE repository is a collection of tools or facilities for creating system models and documentation. These facilities generally include: Diagramming tools –These tool